One patient was discharged and ready to go home when he was told a man in his shared hospital room had tested positive for Covid-19.
A 91-year-old patient, who also shared the room, said the incident had left him "extremely upset".
The elderly patient, who did not want to be named, said the incident also meant he and two others who shared the room at the Edmund Hillary Block at Middlemore Hospital are in lockdown - and won't get to see family members for two weeks because they are isolating.
"I am 91, and have got some serious health issues needing antibiotics and some treatment intravenously so I accept I have to be here. But one of the other patients, he had his departure papers and was ready to go home when this happened," he said.
"What happened has been incredibly stressful to all of us, and now it'd be two weeks before we can get to see our families or loved ones."
The man who tested positive was admitted around 7am on Sunday and was sneezing and coughing when he arrived, the patient said.
At about 10.30am, he overheard conversations from doctors who came in to check the man that he had Covid symptoms.
"They took him for a test, but what horrified us was all these were done without PPE," the man said.
It was only in the afternoon at around 3.30pm that two nurses in full PPE came to take the man away.
"The whole time in between, everyone seemed to have left exposed. We in the room had been sharing the same bathroom with the positive patient," the elderly patient said.
He said the room had been "locked down" since about 5pm yesterday, and the three patients were expected to get a Covid test in the coming days.
The elderly patient said he and another 31-year-old man were vaccinated, but the third person wasn't.
"What happened was negligence, and I'd be watching the 1pm press conference to see what more Grant Robertson has to say," the man said.
His son living in the United States told the Herald this morning he felt distressed, and wanted answers on how things went so horribly wrong.
ACT leader David Seymour said he was working with the man and his family to "seek the answers they deserve".
"The 91-year-old left for hours in a room with a Covid-19 positive patient has today reached out to me, furious at the risks he was exposed to.
"He has told me he is aggrieved, but feels there's nothing that can be done."
Seymour said the patient was put into a general ward despite being symptomatic enough to test for Covid, and left there for hours waiting for a test result.
"It appears there was not adequate PPE use until after the case was discovered.
"Most of us follow the rules to the letter of the law. People are unable to travel to comfort loved ones, not even allowed to attend funerals. To think there would be so much carelessness in a hospital, will frustrate people who have been carefully following the rules."
Deputy PM Grant Robertson said the Covid-positive person in Middlemore entered the hospital on an unrelated matter.
After symptoms emerged they tested positive. Other patients are also being tested as are staff who were on the ward - although all were wearing PPE, Robertson told TVNZ's Breakfast.
He didn't have detailed information but there would no doubt be more to say at the 1pm press conference this afternoon. He understood the situation was disturbing for the patients who were in the same room.
Pressed on why patients were left in the room for up to eight hours after exposure, Robertson said hospitals were very clear on infection prevention protocols and had been "brilliant" so far. But more questions would be asked.